JPH02194132A - Manufacture of metal matrix composite - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for manufacturing a metal matrix composite material in which a matrix metal is reinforced with a ceramic reinforcement by an impregnation pressure casting method, and in particular, The present invention relates to a method for manufacturing a metal matrix composite material that uses inexpensive ceramic particles as a reinforcing material, can maintain an appropriate volume ratio of the reinforcing material in the material, and has excellent strength characteristics.

(Prior Art) In recent years, metal matrix composite materials reinforced with ceramic fibers or ceramic particles such as silicon carbide and alumina have attracted attention as one of the new materials.

Among them, ceramic fibers with excellent high-temperature strength and hardness are used.
Metal matrix composite materials dispersed in a matrix metal are becoming popular in a wide range of industrial fields such as space equipment, robots, automobiles, and aircraft.

Conventionally, the method for manufacturing ceramic IM reinforced composite materials using ceramic fibers such as Ao, 03 fibers, and Si CIIaH as reinforcing materials and aluminum alloy materials as matrix metals has been the molten metal impregnation pressure casting method (hereinafter referred to as "infiltration"). ) is generally adopted.

In this infiltration method, first, a ceramic IIH preform having a predetermined shape and fiber volume fraction (Vf) is formed using ceramic fibers under pressure, and this preform is placed in a mold and heated to 200 to 700°C. Heat. Thereafter, molten aluminum alloy is poured into the mold, and the molten aluminum alloy is directly pressurized with a ram, thereby impregnating m4 into the internal space of the preform to obtain a composite with aluminum alloy as a matrix. be.

By the way, the volume fraction (Vf
) represents the ratio of the volume of the reinforcement to the apparent volume of the preform, which corresponds to the volume ratio of the reinforcement to the volume of the finished composite.

If this volume fraction is too small, its effectiveness as a reinforcing material will be low, while if it is too large, the matrix gold will be relatively less effective.
decreases, the strength to hold the reinforcement decreases, and the mechanical properties of the composite material decrease as well. Therefore, this volume fraction is set in the range where the strength property value of the composite material is maximum,
Its specific value is about 10 to 50%.

On the other hand, 11M-shaped or whisker-shaped ceramics have been mainly used as reinforcing materials, but fibrous and whisker-shaped ceramics are several times more expensive than particulate ceramics because they are secondary processed products. be. As a result, the product price of composite materials has become extremely high, which has been a major obstacle to their practical application.

Therefore, attempts have been made to use more particulate ceramics as a cheaper reinforcing material to create an inexpensive metal matrix composite material.

(Problem to be solved by the invention) However, in the manufacturing process using the conventional infiltration method, the volume ratio is 50% or less using only ceramic particles, and sufficient strength is required to prevent deformation or breakage during pressurized VI manufacturing. It was difficult to form a preform with 1-. In other words, in order to fix the positions of the ceramic particles by intertwining them and form a preform that can withstand pressure operations, the volume fraction must be 50 to 7, as shown in Figure 2.
Ceramic particles 1 must be blended at a high density so that the content is 0%. In that case, ceramic particles 1.1
Since the volume of the void 2 between the two is minute, the volume for impregnating the molten metal serving as the matrix is reduced, and the strength characteristics of the resulting composite material are also reduced.

On the other hand, there are three methods that can form a metal matrix composite material by uniformly dispersing ceramic particles in a matrix metal at a relatively low volume fraction: powder metallurgy, mechanical alloying, and Konhoki 1 distyping. Almost limited.

The powder metallurgy method involves thoroughly mixing raw metal powder as a matrix and ceramic particles as a reinforcing material, then press-molding the resulting mixture and heating it to ^ temperature in a vacuum or inert gas atmosphere. This is a method of composite molding using hot pressing.

In the mechanical alloying method, matrix raw metal and ceramic particles are placed in a stirring tank that also serves as a pulverizer.
In this method, raw materials are mechanically pulverized to a predetermined particle size, thoroughly mixed, a homogeneous mixture is prepared, and the resulting mixture is heated and pressed in the same way as in powder metallurgy to form a composite material.

In addition, in the composite casting method, the matrix raw material is heated until it becomes a semi-molten state in which the liquid phase and solid phase of the raw metal metal coexist, and ceramic particles are added and mixed in this state, and when the particles are uniformly dispersed, the matrix material is・This is a method of solidifying Rix raw materials to form composite materials.

However, the powder metallurgy method and mechanical alloying method require a raw material mixing process, sintering equipment, hot press equipment, vacuum equipment, inert gas equipment, etc., and require more equipment and manufacturing processes than the infiltration method. There are problems such as complexity, low productivity, and rising costs for manufacturing composite materials.

In addition, in the composite casting method, the wettability of the molten metal and the reinforcing material is generally low, and it is often difficult to composite the fine reinforcing material with the matrix metal, which limits the amount of reinforcing material added, and it is difficult to obtain sufficient strength. There was a problem in that it was not possible to obtain a composite material with

The present invention was made to solve the above-mentioned problems, and uses inexpensive ceramic particles as the main reinforcing material, and achieves extremely high performance without using expensive and complicated equipment. ! It is an object of the present invention to provide a method for manufacturing a metal matrix composite material that can be manufactured using heavy-duty equipment, has good workability, and is economical at low cost.

Another object of the present invention is that the preform is not destroyed during impregnation and pressurization, and that the preform as a reinforcing material can be uniformly dispersed at a low volume percentage in the matrix metal. It is an object of the present invention to provide a method for manufacturing a metal matrix composite material that can be produced.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for producing a metal matrix composite material in which a fine reinforcing material is dispersed in a matrix metal material, in which ceramic particles as the reinforcing material are the main component. , forming a preformed body containing at least one of ceramic fibers and ceramic whiskers as a subsidiary component;
The method is characterized in that the preform is impregnated with molten metal as a matrix metal and then pressure cast to form a composite.

In addition, the volume percentage of the reinforcing material in the preform is 10% or more and 50%.
It is recommended to set it as below.

(Function) According to the above configuration, since the main component is ceramic particles as a reinforcing material, and a small amount of reinforcing material consisting of at least one of ceramic fiber HiB and ceramic whiskers is added as a subsidiary component, the ceramic 8N1t-ramix whisker forms a three-dimensional fiber skeleton, and the ceramic particles are firmly bonded along the miscellaneous skeleton, forming a preformed body with high strength as a whole. Each ceramic particle is held on the skeleton in isolation from each other, and wide voids 111 are formed between the ceramic particles, resulting in a preformed body with low bulk density and volume fraction and high strength.

Therefore, even if excessive pressure is applied during impregnation pressure casting, the preform will not be destroyed.
Since the wide voids are sufficiently impregnated with matrix molten metal, a metal matrix composite material with high strength can be provided.

In particular, by setting the volume percentage of the reinforcing material in the preform to 10% or more, the reinforcing effect of the reinforcing material is enhanced, and by setting the volume percentage to 50% or less, the bond between the 7 Trix and the reinforcing material is improved. A metal matrix composite material with increased strength and optimal strength characteristics can be obtained.

Furthermore, according to the method of the present invention, in the process of forming a preform and the composite process of impregnating and pressurizing VI-forming, expensive equipment, equipment that is complicated to operate such as high-temperature, high-vacuum equipment, and atmosphere adjustment equipment is not used. Since the metal matrix composite material can be produced in the atmosphere with extremely simple equipment and operations, the metal matrix composite material can be produced at low cost and with high efficiency.

(Example) Next, an example of the ljj manufacturing method of a metal matrix composite material according to the present invention will be described with reference to the accompanying drawings.

First, as a reinforcing material, SiC particles having an average particle diameter of 5 μm and carbon fibers having an average diameter of 7 μm and a length of 6 mm were mixed so that the volume content ratio of each was 5:1. On this occasion,
Alumina sol was added as a binder in an amount of 10% by weight based on the total weight. After thoroughly mixing the obtained mixture, it was filled into a mold with a diameter of 100 ml, and the height was 10 ml.
Pressure 200/ so that the volume fraction of reinforcing material is 30% at 0 m
Compression molding was performed at l/all to form a preform.

Next, the obtained preform is heated once at 800'C for 4 hours to crystallize the added alumina sol, thereby forming a bond between SIG particles, between carbon am, and between SiC particles and carbon tM, H. Increased bond strength. When the distribution of SiC particles and carbon fibers in the obtained preform was observed using a microscope, it was found that carbon 1113 was intertwined three-dimensionally to form a fiber skeleton, as shown in Figure 1. It was confirmed that the SiC particles 1 were held separated from each other along the lines, and wide voids 2 were formed between the SiC particles 1.1.

In this way, the addition of a small amount of carbon sin reduces the bulk density of the preform, ensuring an optimal volume fraction of the reinforcement, and at the same time, the fiber skeleton formed by the carbon fibers forms a strong preform. be done.

Furthermore, the obtained preformed body was placed in a mold and molten 60
61 aluminum alloy was poured into the mold, and the molten metal was pressurized with a piston at a pressure of 20 (1/li) to impregnate the molten metal into the space inside the preform to form a composite material.

The preform was uniformly dispersed in the aluminum alloy without deformation or crushing during pressure casting, and a high-strength composite material could be obtained.

On the other hand, as a comparative example, an attempt was made to form a preform with a volume fraction of 30% or less by using a reinforcing material consisting only of SiC particles without adding carbon ilN, but due to the high bulk density of the SiC particles, Even with the addition of a binder, it has been impossible to produce a material with high strength that can withstand pressure casting and a volume fraction of 30% or less. Further, the volume fraction, which is the molding limit of the preform that can sufficiently withstand a pressure of about 2008910i and withstand the pressure during casting, exceeded 50%.

The particle distribution state of this preformed body consisting only of SiC particles and having a volume fraction of 50% is as shown in Fig. 2, and is formed between 1.1... of SiC particles accumulated at high density. The void 2 is small. Therefore, the matrix metal I impregnated into the voids 2 is relatively reduced, the retention strength of the SIC particles 1 is reduced, and the strength characteristic value of the composite material as a whole is also reduced.

[Effects of the Invention] As explained above, according to the method for producing a metal matrix composite material according to the present invention, a reinforcement consisting of ceramic particles as a main component and at least one of ceramic fibers and ceramic whiskers as a subsidiary component. Because a small amount of material is added, the ceramic I fibers and ceramic whiskers form a three-dimensional fiber skeleton, and the ceramic particles are firmly bonded along the 8M skeleton, forming a preform with high strength as a whole. Ru. The ceramic particles are held on the skeleton in isolation from each other, and wide voids are formed between the ceramic particles, resulting in a preformed body with low bulk density and volume fraction and high strength.

Therefore, even if excessive pressure is applied during impregnation pressurization, the preform will not be destroyed, and the wide voids will be sufficiently impregnated with the matrix molten metal, resulting in a high-strength metal. A base composite material can be provided.

Furthermore, according to the method of the present invention, in the process of forming the preform and the composite process of impregnating pressure casting, octavalent equipment and
Metal matrix composite materials can be manufactured at low cost and in the atmosphere without the use of complicated equipment such as B-lagoon high-vacuum equipment and atmosphere adjustment equipment. It can be produced with high efficiency.

It is an enlarged view of a part of the female molded body.

DESCRIPTION OF SYMBOLS 1...Ceramics particle (SiC particle), 2...Void i part, 3...Ceramics I1M (carbon fiber).

Claims (1)

[Claims] 1. A method for manufacturing a metal matrix composite material in which fine reinforcing material is dispersed in a matrix metal material, wherein ceramic particles as the reinforcing material are the main component, and at least one of ceramic fibers and ceramic whiskers is used as a secondary component. 1. A method for producing a metal matrix composite material, comprising: forming a preform as a component; impregnating the preform with molten metal as a matrix metal; and pressurizing and casting to form a composite. 2. The volume percentage of reinforcing material in the preform is 10% or more and 50%
The method for producing a metal matrix composite material according to claim 1, characterized in that: